CI: Add Ruby 3.2 (#1298)

Author: sodabrew

.github/workflows/build.yml

@@ -16,6 +16,7 @@ jobs:
           # - ubuntu-20.04 # focal
           - ubuntu-18.04 # bionic
         ruby:
+          - '3.2'
           - '3.1'
           - '3.0'
           - '2.7'